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    <title>Document</title>
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<body>
    <script>
        /* 不确定数量的量词 */
        /* 
        +    1个，或1个以上   m>=1  {1}
        *    0个或多个     m>=0    {0,}
        ?    0,1      {0,1}
        */    
       var reg=/\d?/;
       var str="124edehsd";
       console.log(reg.test(str))  //true

    </script>
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